Cut-out for series lamps



D. S. GUSTIN El" AL CUT-OUT FOR SERIES LAMPS Jan. 2, 1934.

Original Filed June 18. 1929 INVENTORS D. ,5. G05 T/IV fi/ETZ PatentedJan. 2, 1934 CUT-OUT FOR Daniel S. Gustin and SERIES LAMPS Ewald Dietz,Bloomfield,

N. .L, .assignors to Westinghouse Lamp Company, a corporation ofPennsylvania Original application June 18, 1929, Serial No.

371,821. Divided and her 10, 1931.

8 Claims.

This invention relates to the manufacture of incandescent electric lampswhich are burned when connected in series and is a division ofapplication Serial No. 371,821 filed June 18, 1929.

In certain types of incandescent lamps such for example as lampsemployed for our lighting, street series or for Christmas tree lighting,a given number of lamps are connected so that the combined voltage ofthe lamps is equal to the voltage of current supply.

It has been found that when usinga plurality of lamps connected inseries considerable inconvenience occurs upon the failure of one of thelamps if a filament breaks or the lamp structure otherwise fails tooperatensince such failure terminates the continuity of the circuit andthe rest of the lamps are extinguished. It is difficult to determine byinspection which lamp has failed and it becomes necessary, in order toselect the lamp which is defective, to test by trial until the defectivelamp has been discovered, which procedure is obviouslytime consuming andinconvenient.

, The present invention provides a lamp of the series type in which ameans is provided as an integral part of a base to permit a flow ofcurrent upon the failure of the filament or other defeet which mi htprevent the normal flow of current'through the lamp. By the provision ofthe said means the lamp which fails maybe immediately detected inasmuchas the remaining lamps will continue in operation.

Mediums of various characters have heretofore been proposed for thepurpose above set forth but have not been found entirely satisfactoryfrom a practical standpoint. For example, it has been suggested to usealuminum powder disposed within a lamp stem so as to be in contact withthe two leading-in conductors which supply electrical energy to thefilament.

The aluminum powder functioned as a cut out medium which was normallyresistant to the flow of current at a given voltage by reason of anoxide film surrounding each particle of the powder. Upona failure of thefilament, however, the full voltage of the lamp being impressed upon thepowder, the oxide film was broken down causing current to flow from onelead to the other. Various other materials may have been proposed inwhich an oxide forms around the particles. It

has been found that particles having thereon what might be termed, .anaturally formed oxide, provide an insulating layer of. either too greator too small degree for practical commercial purthis application Septem-Scrial No. 562,038

material which did not depend upon a natural oxide on the particles ofthe powdered material gave satisfactory and reliable results; thepresent invention is, however, in the nature of an improvement overmaterials such as the copper sulphide coated copper particles.

In practicing the present invention a cut out element is formed offinely divided copper powder impregnated with or the particles thereofcoated with sodium silicate. The powdered copper particles may or maynot have a layer of an oxide thereon. Preferably the particles are cleanor free from oxide when coated with sodium silicate;

It has been found that by combining sodium silicate and powdered coppera cut out element in the form of .a pellet or button may be constructedby the application of pressure to the powder when in a suitably formedmold. The proportion of sodium silicate to the copper powder may vary inaccordance with the voltage of the lamp. 'It has been found, however,that for use in lamps of from 8 to 70 volts the following procedure willgive a practical cut out element: 100 grams of metallic copper powder ofNo. 150 mesh are mixed with grams of 1.55 specific gravity sodiumsilicate containing approximately 14% alkali and dehydrated at 130centigrade and stirred for 16 hours, after which the mixture is screenedthrough mesh screen. A button or pellet is then formed from this mixtureby taking 100 grams of the same and adding thereto 12 grams of sodiumsilicate and applying a pressure of 3200 pounds per square inch anddrying at 180 centigrade for 3 hours.

The break down voltage of a pellet formed by the above method maybevaried, for example,

an increase of pressure lowers the break down voltage, whereas lesspressure will raisethe break down voltage so that a pellet may be madefor a given break down voltage for use in a given type of lamp.

It will be understood'that when producing a cut out medium in accordancewith the above method the metallic powder when mixed with to a base 14by cement 15.

sodium silicate and dried While in loose powder form, may be used as ashunt or breakdown resistance in a lamp. If used in loose powder formthe medium may be packed in the stem tube and around the lead wires sothat upon a failure of current to pass the filament an overload will beimpressed on the powder permitting a current flow.

When used in button or pellet form as a compact mass the dehydratedparticles of metallic powder having a sodium silicate coating arecombined by a binder of sodium silicate and compressed at the pressureof about 3200 pounds per square inch as above set forth.

It is believed that a heat treatment of the silicate and metallicparticles results in coating the particles with a layer of a complexcopper silicate which has been found to serve as an insulation of therequired degree, 1. e. one which will oppose a flow of current at agiven voltage and break down at a predetermined excess voltage.

When a cut out medium of the present character is incorporated in a lampand the filament fails, causing the electrical energy to flow across thecut out medium, a copper silicate slag is formed and a path providedover which the electrical energy flows.

Although copper powder and sodium silicate has been found preferable asa cut out, a medium for this purpose may be produced by using aluminumpowder and sodium silicate or iron powder and sodium silicate may beused.

It will be understood that the present invention is directed broadly tothe combination of an insulating material which is artificially appliedto metallic particles as distinguished from a naturally produced layerof insulation as when an oxide forms naturally or is forced as by heat.The present invention may be practiced by using conductive particlesencased in layers of insulating material such as a bakelite solution orother non-conductive varnishes or coatings may be used.

The application of the pellet to a lamp base will be more fullyunderstood by reference to the accompanying drawing in which;

Fig. 1 is a vertical sectional view of a portion of a lamp bulb with abase attached thereto.

Fig. 2 is an enlarged transverse cross sectional view of the base takenon line II-II in Fig. 1.

Fig. 3 is a perspective view of a pellet and holder partly in crosssection, and

Fig. 4 is a perspective view of a cup or supporting member for holding apellet in position in a base.

Although the present material may be used as a cut out medium bydisposing the same in various positions in a lamp, it has been foundpractical to employ the cut out material in the form of a pelletsurrounding one of the lead wires of the lamp.

As illustrated a lamp 10 having the usual stem 11 and lead wires 12 and13 may be connected The base 14 is generally composed of a shell 16having a bottom contact member 17 supported in a ring 18 of insulativematerial such as glass. The lead wire 12 may be connected by solder 19to the brass shell 16 and the leading in wire 13 may extend through thebase and be secured by solder 20 to the contact 17.

In accordance with the present invention a pellet 21 is disposed in thebase and the lead wire 13 extends through an aperture 22 in the pellet.The said pellet is carried in a support member or bracket 23 havingspring arms 24 and 25 which extend outwardly and engage the internallythreaded portion 26 of the base. By reason of the formation of the arms24 and 25 the pellet may be screwed into the base and in contact withthe insulative ring 18, The bracket 23 may be constructed in the form ofa cup having an annular flange 2'7 and a bottom flange 28. A pluralityof clips 29 may be provided to engage the pellet and hold it in positionor the said clips may extend from the flange 27 and may be embedded inthe pellet during its formation as when molded in the cup underpressure.

The lead wire 13 may extend through the aperture 22 of the pellet andmake direct contact therewith. It has been found preferable, however, toprovide the aperture 22 with a conical or flared mouth to receive theconical shaped metallic contact element 30. Thus the lead wire 13 mayreadily be threaded through the aperture 22 and it may engage with thecontact 30. By

reason of the said contact the effective contact area between the leadwire 13 and the pellet 21 is greater than would be the case if the leadwire made direct contact with the wall of the aperture 22. When a pellethas been incorporated in a base and the filament of the lamp fails sothat the entire load is thrown across the pellet, current will flow fromcontact 17 through the lead 13 through contact element 30, thencethrough the pellet material and the metallic support 23 which is indirect contact with the shell 16. A complete circuit is thus providedand as the pellet offers the proper degree of resistance the continuityof the flow of energy would be maintained and the remaining lamps of theseries will continue to operate. When producing a cut out element forthe above purpose the method hereinbefore described may be utilized andthe mixed sodium silicate and copper powder may be placed in the bracketor cup 23 and molded to form under the required pressure.

Although it has been found practical and convenient to use a disc orpellet it is obvious that the present material consisting of a metallicpowder mixed with or impregnated with sodium silicate. may be employedas a cut out in various ways. For example, the entire base may be filledwith the cut out material or a quantity or body of the said material maybe disposed within the stem 11 so as to surround the lead wires 12 and13, and although the present illustration sets forth a preferredembodiment of the invention, other modifications may suggest themselveswithout departing from the spirit and scope of the present invention asset forth in the appended claims.

What is claimed is:

1. An incandescent electric lamp comprising a base, a pellet consistingof a compact mass of metallic powder and sodium silicate disposed in sad base, a metallic support for said pellet, a lead wire of said lamp incontact with one portion of said pellet, an electrical conductor incontact with another portion of said pellet and in contact with saidbase, said support serving to carry said pellet and for holding saidpellet removably within said base.

2. An incandescent electric lamp comprising a 7 and a lead wire of saidlamp in contact with said pellet.

3. An incandescent electric lamp comprising a base, a removableresistance element including a disk resistant to the flow of electricalenergy at a given voltage and a metallic support for said disk, saiddisk having an aperture to receive a contacting lead wire of said lampand means for electrically connecting said support with said base.

4. A cut out element for an incandescent electric lamp comprising acompact mass of resistance material, a conductive member embedded insaid mass and conductive members in electrical contact with said massand extending therefrom for engagement with the wall of a lamp base.

5. A resistance element for disposition in the base of an incandescentelectric lamp comprising a pellet of compact resistance material, aconductive member embedded in said pellet for contact with a lead wireof a lamp and conductive extensions for engaging the wall of said baseto support said pellet and for electrically connecting said pellet withthe base of said lamp.

6. A resistance element for a lamp base comprising a pellet of aresistance material, a contact element embedded in said material andsupporting electrical conductors for electrically connecting andsupporting said pellet in space relation to the wall of the base.

7. An incandescent electric lamp comprising a base, a disk resistant tothe flow of electrical energy at a given voltage, metallic membersextending from said disk to electrically connect and support said diskin spaced relation to the wall of said base and a tubular contact memberembedded in said disk to receive a lead wire of said lamp.

8. An incandescent electric lamp comprising a base having a bottomcontact, a resistance element consisting of a compact mass of resistancematerial, means for supporting: said mass in spaced relation to the wallof the base, a metallic eyelet in said mass to provide a passagetherethrough, one of the lead wires of said lamp extending through saideyelet and in electrical contact with the wall thereof, said lead wirebeing electrically connected to said bottom contact.

DANIEL S. GUSTIN. EWALD DIETZ.

